An arc fault circuit interrupter has an arc detection device used to detect hazardous arcing events on a circuit, and in response, to trip a circuit interrupter and remove power to the circuit. These arc fault devices may include circuit breakers such as Combination Arc Fault Circuit Interrupters (for parallel and series arcs) and include Dual Function (Arc Fault (AF) and Ground Fault (GF)) circuit interrupters. Circuit interrupter devices other than circuit breakers might be placed at outlet receptacles or the like.
Traditional arc fault detection requires monitoring load current, thus only the line conductor (i.e. the hot wire of a single pole circuit) is passed through the core of the current transformer. In ground fault sensing, the differential current is monitored and thus both the line and the neutral conductors of the one pole circuit are passed through the core of the current transformer sensor.
For a traditional dual function (arc fault and ground fault) circuit breaker, two current sensors or more are utilized, one sensor being a current transformer for the arc fault detection and a second current transformer being for the ground fault detection. It will be appreciated that component space and overall cost are always limiting factors for circuit interruption devices and especially in the miniature circuit breaker market. The reader is referred to U.S. Pat. No. 6,538,863 to MacBeth for a further overview of these concerns. MacBeth has suggested a so-called “asymmetric winding” for a traditional current transformer involving either a half winding or a tapped winding as a means to achieve arc fault and ground fault functionality with a single current transformer, but leading to a double set of signal chains, one for ground fault and one for arc fault.